Orit Raz

Positive Surgical Margin Appears to Have Negligible Impact on Survival of Renal Cell Carcinomas Treated by Nephron-Sparing Surgery

BACKGROUND The occurrence of positive surgical margins (PSMs) after partial nephrectomy (PN) is rare, and little is known about their natural history. OBJECTIVE To identify predictive factors of cancer recurrence and related death in patients having a PSM following PN. DESIGN, SETTING, AND PARTICIPANTS Some 111 patients with a PSM were identified from a multicentre retrospective survey and were compared with 664 negative surgical margin (NSM) patients. A second cohort of NSM patients was created by matching NSM to PSM for indication, tumour size, and tumour grade. MEASUREMENTS PSM and NSM patients were compared using student t tests and chi-square tests on independent samples. A Cox proportional hazards regression model was used to test the independent effects of clinical and pathologic variables on survival. RESULTS AND LIMITATIONS Mean age at diagnosis was 61+/-12.5 yr. Mean tumour size was 3.5+/-2 cm. Imperative indications accounted for 39% (43 of 111) of the cases. Some 18 patients (16%) underwent a second surgery (partial or total nephrectomy). With a mean follow-up of 37 mo, 11 patients (10%) had recurrences and 12 patients (11%) died, including 6 patients (5.4%) who died of cancer progression. Some 91% (10 of 11) of the patients who had recurrences and 83% of the patients (10 of 12) who died belonged to the group with imperative surgical indications. Rates of recurrence-free survival, of cancer-specific survival, and of overall survival were the same among NSM patients and PSM patients. The multivariable Cox model showed that the two variables that could predict recurrence were the indication (p=0.017) and tumour location (p=0.02). No other variable, including PSM status, had any effect on recurrence. None of the studied parameters had any effect on the rate of cancer-specific survival. CONCLUSIONS PSM status occurs more frequently in cases in which surgery is imperative and is associated with an increased risk of recurrence, but PSM status does not appear to influence cancer-specific survival. Additional follow-up is needed.

Positive surgical margins with renal cell carcinoma have a limited influence on long-term oncological outcomes of nephron sparing surgery.

OBJECTIVES To define the rate of positive surgical margins (PSMs) and analyze the outcome of patients with PSMs. The outcome and proper management of patients with positive PSMs during nephron sparing surgery (NSS) are questionable. In this study we define the clinical outcomes of PSMs at NSS and suggest management. METHODS Clinical records of 114 renal units who underwent open NSS for a renal mass between May 1995 and September 2005 were reviewed. RESULTS PSMs were suspected on frozen section in 17 of 114 renal units (15%). Tumors with suspected PSMs at frozen section were smaller (2.9 +/- 1.6) in comparison to those with negative surgical margins (3.4 +/- 1.8 cm) (P = .001). Nine of 17 (53%) cases underwent total nephrectomy (5 immediately, 4 delayed). In 4 (24%), immediate re-excision of the renal crater was performed. A total of 4 (24%) that were followed up clinically were with no evidence of disease. Therefore, in 13 of 17 (77%) cases, the presence of tumor cells at the remaining side of the kidney could be evaluated histologically. In 2 cases from the immediate response group, tumor cells were found in the side opposite to the resection. There was no residual tumor in any case subjected to delayed nephrectomy. At median follow-up of 71 months, 15 of 17 patients are alive and with no evidence of disease. Two patients died because of unrelated causes. The overall 5-year survival rate is 98.2% and there is no cancer-specific mortality. CONCLUSIONS The true PSM rate is in the range of 1.75%-5.26%. No disease progression or deaths attributable to renal cell carcinoma were associated with PSMs. Total nephrectomy should be avoided as a response to PSMs.

Polynomials vanishing on grids: The Elekes-Rónyai problem revisited

In this paper we characterize real bivariate polynomials which have a small range over large Cartesian products. We show that for every constant-degree bivariate real polynomial f, either |f(A, B)| = Ω(n4/3), for every pair of finite sets A, B ⊂ R, with |A| = |B| = n (where the constant of proportionality depends on deg f), or else f must be of one of the special forms f(u, v) = h(ϕ(u) + ψ(v)), or f(u, v) = h(ϕ(u) · ψ(v)), for some univariate polynomials ϕ, ψ, h over R. This significantly improves a result of Elekes and Rónyai [7]. Our results are cast in a more general form, in which we give an upper bound for the number of zeros of z = f(x, y) on a triple Cartesian product A × B × C, when the sizes |A|, |B|, |C| need not be the same; the upper bound is O(n11/6) when |A| = |B| = |C| = n, where the constant of proportionality depends on deg f, unless f has one of the aforementioned special forms. This result provides a unified tool for improving bounds in various Erdős-type problems in geometry and additive combinatorics. Several applications of our results to problems of these kinds are presented. For example, we show that the number of distinct distances between n points lying on a constant-degree parametric algebraic curve which does not contain a line, in any dimension, is Ω(n4/3), extending the result of Pach and de Zeeuw [19] and improving the bound of Charalambides [2], for the special case where the curve under consideration has a polynomial parameterization. We also derive improved lower bounds for several variants of the sum-product problem in additive combinatorics.

Testicular sparing surgery for small masses

OBJECTIVES To determine the proportion of benign testicular lesions among candidates for testicular sparing surgery (TSS) and to assess the safety and efficacy of this procedure. METHODS AND MATERIALS Sixteen patients underwent surgical exploration for testicular tumors with TSS intent in our center. Surgery was performed via an inguinal approach with temporary cord occlusion and frozen section (FS) analysis of the lesions. Benign findings allowed for TSS, whereas cancer prompted total orchiectomy. RESULTS The lesions measured 8-25 mm in the largest diameter. Eleven of the 16 lesions were benign (69%) and TSS was accomplished in these cases. Complete concordance was observed between the results of FS and permanent sections. Of the 5 patients with cancer, 3 had pure seminoma, and embryonal carcinoma and teratoma were found in 1 patient, each. Surveillance was applied in 4 of these patients, and chemotherapy was used in the patient with embryonal carcinoma. With an average follow-up duration of 48 months, all are alive and free of disease. All 11 patients in whom TSS was accomplished had an uneventful postoperative course, and with an average follow-up duration of 28 months, 9 have normal scrotal physical examination and ultrasound, whereas 2 patients were lost to follow-up. CONCLUSIONS Sixty-nine percent of testicular lesions under 25 mm are benign. TSS is safe and effective in patients with small benign lesions. Cancer is reliably detected by FS, and testicular exploration is not associated with local or distant recurrence in any of our patients.

Polynomials vanishing on Cartesian products: The Elekes–Szabó theorem revisited

Let F 2 C[x; y; z] be a constant-degree polynomial, and let A; B; C subset of C be finite sets of size n. We show that F vanishes on at most O(n(11/6))points of the Cartesian product A X B X C, unless F has a special group-related form. This improves a theorem of Elekes and Szab and generalizes a result of Raz, Sharir, and Solymosi. The same statement holds over R, and a similar statement holds when A; B; C have different sizes (with a more involved bound replacing O(n(11/6)). This result provides a unified tool for improving bounds in various Erdos-type problems in combinatorial geometry, and we discuss several applications of this kind.

Sets with few distinct distances do not have heavy lines

Let P be a set of n points in the plane that determines at most n / 5 distinct distances. We show that no line can contain more than O ( n 43 / 52 polylog ( n ) ) points of P . We also show a similar result for rectangular distances, equivalent to distances in the Minkowski plane, where the distance between a pair of points is the area of the axis-parallel rectangle that they span.

Use of Adult Criteria for Slice Imaging May Limit Unnecessary Radiation Exposure in Children Presenting With Hematuria and Blunt Abdominal Trauma

OBJECTIVE To examine whether it would be safe to use adult criteria for imaging in pediatric blunt renal trauma and hematuria. MATERIAL AND METHODS From 1999 to 2007, 46 consecutive children were admitted for renal trauma and hematuria. All had abdominal computed tomography (CT) scan. Patients were divided into 2 groups: microhematuria and macrohematuria. Outcomes analyzed were presence of renal injury per CT, grade of renal injury, and indication for and details of surgical intervention. RESULTS Twenty-seven patients (59%) had microhematuria. Nineteen (41%) had macrohematuria. On abdominal CT scan, no injury was found in 18 patients with microhematuria (67%) and 3 (16%) with macrohematuria. Two microhematuria patients required surgical intervention. In both cases, no actual renal intervention was performed during surgery. Three macrohematuria patients required surgical intervention; all had renal relevant procedures. The performance of the macro-microhematuria distinction in the prediction of renal injury on CT scan is relatively poor: sensitivity 59%, specificity 14%, positive predictive value (PPV) 84%, and negative predictive value (NPV) 62%, whereas the performance of macrohematuria criteria in the prediction of renal-relevant injury is sensitivity 100%, specificity 61%, PPV 18%, and NPV 93%. CONCLUSIONS The yield of abdominal CT in pediatric renal trauma is low in patients presenting with microhematuria. Our data suggest that it may be possible that adult criteria for renal imaging are sufficient for children with abdominal blunt trauma and microhematuria. Adopting such strategy will result in substantial reduction in exposure to radiation, supposedly without increasing the patients risk.

The predominance of benign histology in small testicular masses.

OBJECTIVES To evaluate the concordance between testicular tumor size and benign histology in order to identify a cut-off size, below which the rate of benign lesions would be highest. METHODS AND MATERIALS During the years 1995-2008, we performed 131 consecutive testicular operations for testicular tumors. Ten of these were testicular preserving surgery, whereas the other 121 patients had radical orchiectomy. We searched for the rate of benign lesions in the following 3 groups of tumor diameter: 10 mm or less, 11-20 mm, and greater than 20 mm. ROC analysis was used to find the optimal size cut-off below which the rate of benign lesions would be highest. RESULTS Benign lesions were found in 11 patients (8%), including epidermoid cyst (n = 4), Leydig cell tumor (n = 3), fibrosis (n = 1), adenomatoid tumor (n = 2), and 1 patient with a simple cyst. Small tumor size strongly correlated with benign histology. The mean diameter of benign vs. malignant lesions was 15 mm and 41 mm, respectively (P < 0.05). The rate of benign lesions in tumors with a diameter of 10 mm or less, 11-20 mm and greater than 20 mm was 50%, 17%, and 2%, respectively. Receiver Operating characteristic (ROC) analysis with 87% sensitivity and 83% specificity revealed a cut-off value of 18.5 mm tumor diameter below which the proportion of benign lesions was 38.5% compared with 2% above it (P < 0.05). CONCLUSIONS While benign lesions comprise only 8% of all testicular tumors, their proportion among small lesions is much higher. With a size cut-off of 18.5 mm, 38.5% of smaller lesions are benign. These findings support consideration of testicular exploration for small testicular lesions aiming at preservation rather than predetermined radical orchiectomy.

Minimum Partial-Matching and Hausdorff RMS-Distance under Translation: Combinatorics and Algorithms

We consider the RMS-distance (sum of squared distances between pairs of points) under translation between two point sets in the plane. In the Hausdorff setup, each point is paired to its nearest neighbor in the other set. We develop algorithms for finding a local minimum in near-linear time on the line, and in nearly quadratic time in the plane. These improve substantially the worst-case behavior of the popular ICP heuristics for solving this problem. In the partial-matching setup, each point in the smaller set is matched to a distinct point in the bigger set. Although the problem is not known to be polynomial, we establish several structural properties of the underlying subdivision of the plane and derive improved bounds on its complexity. In addition, we show how to compute a local minimum of the partial-matching RMS-distance under translation, in polynomial time.

The Number of Unit-Area Triangles in the Plane: Theme and Variations

We show that the number of unit-area triangles determined by a set